For the first time in the United States, a man at a Dallas hospital has been diagnosed with Ebola. Now his sister claims that he notified health care workers about his trip from Liberia.

The man, identified in an Associated Press report as Thomas Eric Duncan, visited an emergency room in Dallas on Friday, where doctors initially sent him home with antibiotics. According to his sister, identified by AP as Mai Wureh, he returned to the hospital when his condition became worse and had to be admitted to Texas Health Presbyterian Hospital.

The government, citing privacy concerns, has not confirmed the identity of the patient infected with Ebola. Dr. Tom Frieden, the director of the Centers for Disease Control and Prevention, noted that the patient arrived in the U.S. from Liberia on Sept. 20 and sought medical help on Sept. 27. The doctor later said the patient went into isolation on Sept. 28.

Medical tests today confirmed the Ebola diagnosis. Officials at the White House said Frieden has briefed President Obama about the patient.

However, the disease can only spread via bodily fluids by someone who traveled to Africa recently and had symptoms of Ebola, which include fever, heavy vomiting, and diarrhea. According to a USA Today report, more serious cases can make people vomit blood and suffer severe abdominal pain.

Frieden is confident that the U.S. will not have an Ebola outbreak, noting that passengers who flew on the same plane with the patient did not contract the disease.

"There is no doubt in my mind we will stop it here," he said.

However, Texas Gov. Rick Perry came out in a press conference today and said that five children may have been exposed to Ebola by the patient.

"Let me assure you, these children have been identified and are being monitored," Perry said.

Officials noted that the five students who had contact with the patient exhibited no symptoms earlier in the week. The schools where the five students went, including one not attended by any of them, will have extra health workers and custodians as a precaution.

"We have a seven-person team in Dallas working with the local health department and the hospital, and we will be identifying everyone who may have come in contact with him and then monitoring them for 21 days," Frieden said.

Frieden said that the primary focus is on the patient's safety as well as the well-being of the people treating him.

Since the outbreak began in March, an ABC News report says that Ebola has killed 2,917 people and infected 3,346 people. While Ebola patients have been previously treated in the United States, they all came into contact with it in West Africa.